NCT06011876

Brief Summary

Acute intermittent hypoxia (AIH) involves brief (1 min), repeated episodes (\~15) of breathing low oxygen air to stimulate spinal neuroplasticity. Animal and human studies show that AIH improves motor function after spinal cord injury, particularly with slightly increased carbon dioxide (hypercapnic AIH; AIHH) and task-specific training. Using a double blind cross-over design, the study will test whether AIHH improves breathing more than AIH and whether specific genetic variations are related to individuals' intervention responses.

Trial Health

77
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
62

participants targeted

Target at P50-P75 for not_applicable

Timeline
16mo left

Started Dec 2023

Longer than P75 for not_applicable

Geographic Reach
1 country

1 active site

Status
recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Progress64%
Dec 2023Sep 2027

First Submitted

Initial submission to the registry

August 1, 2023

Completed
24 days until next milestone

First Posted

Study publicly available on registry

August 25, 2023

Completed
4 months until next milestone

Study Start

First participant enrolled

December 21, 2023

Completed
3.5 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

July 1, 2027

Expected
2 months until next milestone

Study Completion

Last participant's last visit for all outcomes

September 1, 2027

Last Updated

November 5, 2025

Status Verified

November 1, 2025

Enrollment Period

3.5 years

First QC Date

August 1, 2023

Last Update Submit

November 3, 2025

Conditions

Spinal Cord Injuries

Keywords

acute intermittent hypoxiaspinal cord injurybreathingmotor function

Outcome Measures

Primary Outcomes (3)

  • Change in motor evoked potential

    The change in peak-to-peak amplitude of the motor evoked potential of the diaphragm will be tested using transcranial magnetic stimulation.

    Baseline, and 45-60 minutes after intervention on AIH day, AIHH day, and Sham AIH day

  • Change in maximal inspiratory pressure

    Maximal inspiratory pressure is a non-invasive measure of the maximal force achieved when breathing in against an occluded airway.

    Baseline, 1 day, 3 days, and 7 days after intervention blocks (daily AIH + respiratory strength training, daily AIHH + respiratory strength training, daily sham AIH + respiratory strength training.)

  • Change in maximal expiratory pressure

    Maximal expiratory pressure is a non-invasive measure of the maximal force achieved when breathing out against an occluded airway.

    Baseline, 1 day, 3 days, and 7 days after intervention blocks (daily AIH + respiratory strength training, daily AIHH + respiratory strength training, daily sham AIH + respiratory strength training.)

Study Arms (2)

Single-session testing days

EXPERIMENTAL

Participants will complete three separate single-session testing days. Baseline testing will be performed, then on each day, participants will receive AIH, AIHH, and sham AIH in random order. Post-testing will occur after each intervention.

Other: Acute Intermittent Hypoxia (AIH)Other: Acute Intermittent Hypercapnic-Hypoxia (AIHH)Other: Sham AIH

Respiratory strength training blocks

EXPERIMENTAL

Participants will complete three separate respiratory strength training blocks. In each block, participants will receive 5 days of AIH, 5 days of AIHH, and 5 days of sham AIH in random order, followed by respiratory strength training. Each block will include 5 days of intervention and training, and post-testing 1, 3, and 7 days after intervention and training has concluded.

Other: Acute Intermittent Hypoxia (AIH)Other: Acute Intermittent Hypercapnic-Hypoxia (AIHH)Other: Sham AIH

Interventions

Acute Intermittent Hypoxia (AIH)OTHER

AIH (acute intermittent hypoxia) consists of short episodes of low oxygen (9% O2).

Respiratory strength training blocksSingle-session testing days
Acute Intermittent Hypercapnic-Hypoxia (AIHH)OTHER

AIHH consists of short episodes of low oxygen (9% O2) and elevated carbon dioxide (4% CO2).

Respiratory strength training blocksSingle-session testing days
Sham AIHOTHER

A single session of sham AIH with episodes of normal room air (21% O2).

Respiratory strength training blocksSingle-session testing days

Eligibility Criteria

Age18 Years - 70 Years
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • Adults 18-70 years of age
  • Chronic incomplete SCI ≥ 1 year at or below C1-T12
  • Incomplete SCI based on residual sensory and motor function below the level of the injury or injury classification of B, C, D at initial screening according to the American Spinal Injury Association Impairment Classification and the International Standards for the Neurological Classification of SCI.
  • OR- Chronic complete SCI ≥1 year at or below C4-T12
  • Complete SCI based on the absence of residual sensory or motor function below the level of injury or injury classification of A at initial screening according to the American Spinal Injury Association Impairment Classification and the International Standards for the Neurological Classification of SCI.
  • Medically stable with physician clearance
  • SCI due to non-progressive etiology
  • % impairment in maximal inspiratory, maximal expiratory pressure generation, or both relative to normative values

You may not qualify if:

  • Current diagnosis of an additional neurologic condition such as Multiple Sclerosis, Parkinson disease, stroke, or brain injury
  • Severe illness or infection, including non-healing decubitus ulcers, untreated bladder or urinary tract infections, cardiovascular disease, lung disease, active heterotopic ossification, or uncontrolled hypertension
  • Severe neuropathic pain
  • Known pregnancy
  • Severe recurrent autonomic dysreflexia

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Brooks Rehabilitation

Jacksonville, Florida, 32216, United States

RECRUITING

MeSH Terms

Conditions

Spinal Cord InjuriesRespiratory Aspiration

Condition Hierarchy (Ancestors)

Spinal Cord DiseasesCentral Nervous System DiseasesNervous System DiseasesTrauma, Nervous SystemWounds and InjuriesRespiration DisordersRespiratory Tract DiseasesPathologic ProcessesPathological Conditions, Signs and Symptoms

Study Officials

  • Emily Fox, DPT, MHS, PhD

    University of Florida & Brooks Rehabilitation

    PRINCIPAL INVESTIGATOR

Central Study Contacts

Emily J Fox, PT, MHS, PhD

CONTACT

904-742-2500ejfox@phhp.ufl.edu

Hannah Snyder, M.S.

CONTACT

904-345-6910Hannah.snyder@brooksrehab.org

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
DOUBLE
Who Masked
PARTICIPANT, INVESTIGATOR
Purpose
TREATMENT
Intervention Model
CROSSOVER
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

August 1, 2023

First Posted

August 25, 2023

Study Start

December 21, 2023

Primary Completion (Estimated)

July 1, 2027

Study Completion (Estimated)

September 1, 2027

Last Updated

November 5, 2025

Record last verified: 2025-11

Data Sharing

IPD Sharing
Will not share

Locations

US(1)